Supraglottic airway

(Redirected from Laryngeal Mask Airway (LMA))

Indications

  • Need for positive pressure ventilation (PPV)
    • Can be used both as primary and rescue airway (if BVM or intubation fail)[1]
    • Can also be used as a conduit/guide for elective or rescue fiberoptic intubation[2]
  • LMA better than endotracheal for paramedics, especially in pediatric patients[3][4]

Contraindications

Absolute

  • Spontaneous respirations
  • Gag reflex

Relative

  • Significant facial trauma

Difficult Supraglottic Device (RODS)

  • Restricted motnh opening
  • Obstruction
  • Distorted airway
  • Stiff lungs or neck (c-spine)

Equipment Needed

  • Supraglottic Airway (SGA) device (many options exist, see below)
  • Appropriate sedation/paralytic agents, if indicated

LMA Sizes[5]

Mask Size Weight (kg) Age (yr) LMA Length (cm) LMA Cuff Vol (mL) Largest ETT^ (mm)
1 <5 <0.5 10 4 3.5
1.5 5-10 <1 10 5-7 4
2 6.5-20 1-5 11.5 7-10 4.5
2.5 20-30 5-10 12.5 14 5
3 30-60 10-15 19 15-20 6
4 60-80 >15 19 25-30 6.5
5 >80 >15 19 30-40 7

^Largest ETT that can pass thorough "Intubating LMA" (ILMA)

iGel Sizes

igel size patient size weight (kg)
1 neonate 2-5
1.5 infant 5-12
2 smal pediatric 10-25
2.5 large pediatric 25-35
3 small adult 30-60
4 medium adult 50-90
5 large adult 90+

Procedure

Due to variety of devices and placement techniques, impossible to give exact universal procedure

  • Prepare patient (appropriate positioning, preoxygenate, pretreatment if indicated)
    • Topical anesthetic to posterior oropharyngeal mucosa may be beneficial in awake Intubation/LMA placement.
  • Induction
  • Paralyze (if indicated)
  • Place supraglottic airway device - possible techniques include[6]:
    • Use thumb/index finger to guide SGA along midline of hard palate (cuff deflated or partially inflated, if possible) - advance until seated
    • Insert SGA with cuff facing hard palate, then rotate 180 degrees while advancing (similar to OPA insertion)
    • Insert laterally 45 degrees against tongue, advance and rotate to midline
  • Inflate cuff (if applicable)
  • Confirm placement (CXR, etCO2, lung sounds, listen for oropharyngeal air leak)

Complications[1]

  • Bronchospasm
  • Hoarseness
  • Laryngeal nerve injury
  • Hypoglossal nerve injury
  • Pharyngeal edema
  • Dysphagia

Special Considerations

  • There are 2 generations of supraglottic airway devices[7][2]
    • 1st Gen = classic LMA, other standard LMAs
    • 2nd Gen = iGel, LMA Supreme, Pro-Seal LMA (PLMA)
  • Second generation devices achieve improved esophageal and pharyngeal seal (causes ↑ oropharyngeal leak pressure), incorporate a "drain tube" that allows access to the esophagus and stomach, and usually have an incorporated bite block.
  • Oropharyngeal leak pressure = the applied pressure at which the seal between the device and the larynx begins to leak.
    • Peak inspiratory pressure needs to be less than the oropharyngeal leak pressure for effective ventilation and to prevent gastric insufflation.[6]
  • Higher failure rate with obese patients, inappropriate patient position (e.g. trendelenberg), and placement by inexperienced provider[2]

See Also

References

  1. 1.0 1.1 Apfelbaum JL, et al.; American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology. 2013 Feb;118(2):251-70
  2. 2.0 2.1 2.2 Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Cook TM, Woodall N, Frerk C; Fourth National Audit Project. Br J Anaesth. 2011 May;106(5)
  3. Zhu X-Y, Lin B-C, Zhang Q-S, Ye H-M, Yu R-J. A prospective evaluation of the efficacy of the laryngeal mask airway during neonatal resuscitation. Resuscitation. 2011;82(11):1405–1409. doi:10.1016/j.resuscitation.2011.06.010
  4. Calkins MD, Robinson TD. Combat trauma airway management: endotracheal intubation versus laryngeal mask airway versus combitube use by Navy SEAL and Reconnaissance combat corpsmen. J Trauma. 1999;46(5):927–932
  5. Tarascon Adult Emergency Pocketbook
  6. 6.0 6.1 Patel B., Bingham R. Laryngeal mask airway and other supraglottic airway devices in paediatric practice. Contin Educ Anaesth Crit Care Pain (2009) 9 (1): 6-9.
  7. Timmermann, A. Supraglottic airways in difficult airway management: successes, failures, use and misuse. Anaesthesia, 2011, 66(Suppl. 2), pages 45–56.